Display panel and method for manufacturing the same

ABSTRACT

A display panel and a method for manufacturing the same are provided. The display panel includes: a base substrate; a first electrode layer on a side of the base substrate; a light emitting layer on a side of the first electrode layer facing away from the base substrate; and a second electrode layer on a side of the light emitting layer facing away from the first electrode layer, wherein the second electrode layer has a first surface which is a roughened surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Chinese Patent Application No.201810834313.5 filed on Jul. 26, 2018 with the China National Intellectual Property Administration, the disclosure of which is incorporated herein in entirety by reference.

TECHNICAL FIELD

The present disclosure relates to the field of display technologies, and more particularly to a display panel and a method for manufacturing the display panel.

BACKGROUND

As QLED (Quantum Dot Light Emitting Diode) display apparatuses develop, stability and luminous efficiency of quantum dots increase continuously. Thus, the QLED display apparatuses have become more and more important in the display field. However, in the QLED display apparatuses having a top emission structure, micro cavities will be adjusted in a narrow efficient range due to narrow spectrum of quantum dots. It often may cause luminous energy loss of quantum dot light emitting diodes to degrade quality of the QLED display apparatuses.

SUMMARY

Embodiments of the present disclosure provide a display panel including: a base substrate; a first electrode layer on a side of the base substrate; a light emitting layer on a side of the first electrode layer facing away from the base substrate; and a second electrode layer on a side of the light emitting layer facing away from the first electrode layer, wherein the second electrode layer has a first surface which is a roughened surface.

In some embodiments, the first surface is located on a side of the second electrode layer facing away from the light emitting layer.

In some embodiments, a plurality of protrusions are distributed on the first surface.

In some embodiments, the light emitting layer is a quantum dot layer.

In some embodiments, the display panel further includes: a second transport layer between the second electrode layer and the light emitting layer, the second transport layer having a second surface which is a roughened surface.

In some embodiments, the second surface is located on a side of the second transport layer facing towards the second electrode layer or on another side of the second transport layer facing towards the light emitting layer.

In some embodiments, the display panel further includes: a first transport layer on a side of the light emitting layer facing towards the first electrode layer; and a first injection layer on a side of the first transport layer facing towards the first electrode layer, wherein at least one of the first transport layer and the first injection layer has a third surface which is a roughened surface.

In some embodiments, the third surface is a surface of the at least one of the first transport layer and the first injection layer facing towards the second electrode layer, or a surface of the at least one of the first transport layer and the first injection layer facing towards the base substrate.

In some embodiments, the first transport layer is a hole transport layer and the first injection layer is a hole injection layer.

In some embodiments, the second electrode layer is an indium tin oxide layer or an indium zinc oxide layer.

Embodiments of the present disclosure provide a method for manufacturing a display panel, the method including: arranging a first mask on a side of a base substrate, the first mask comprising a first transmission portion and a first shielding portion; arranging a second mask on a side of the first mask facing away from the base substrate and locating an orthographic projection of a pattern of the second mask onto the first mask within the first transmission portion of the first mask; and forming a second electrode layer with a roughened surface of the display panel in a region of the base substrate exposed from the first transmission portion of the first mask, by means of sputtering through the second mask.

In some embodiments, the arranging the first mask on the side of the base substrate comprises: keeping the first mask in contact with the base substrate.

In some embodiments, the arranging the second mask on the side of the first mask facing away from the base substrate and locating the orthographic projection of the pattern of the second mask onto the first mask within the first transmission portion of the first mask comprises: keeping a gap between the first mask and the second mask.

In some embodiments, the second mask comprises: a second shielding portion; and a plurality of second transmission portions separated from one another by the second shielding portion.

In some embodiments, before arranging the first mask on the side of the base substrate, the method further comprises: forming a first electrode layer on the base substrate; forming a light emitting layer on the first electrode layer; and forming a second transmission layer on the light emitting layer.

In some embodiments, after forming the first electrode layer on the base substrate and before forming the light emitting layer on the first electrode layer, the method further comprises: forming a first injection layer and a first transport layer in sequence on the first electrode layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a structure of a display panel in accordance with embodiments of the present disclosure;

FIG. 2 is a schematic view showing a structure of a second electrode layer shown in FIG. 1;

FIG. 3 schematically illustrates structures obtained in steps of a method for manufacturing a display panel in accordance with embodiments of the present disclosure;

FIG. 4 is a front view of a first mask shown in FIG. 3;

FIG. 5 is a flow chart of a method for manufacturing a display panel in accordance with embodiments of the present disclosure;

FIG. 6 is a schematic view showing a structure of another display panel in accordance with embodiments of the present disclosure;

FIG. 7 is a schematic view showing a structure of a further display panel in accordance with embodiments of the present disclosure; and

FIG. 8A and FIG. 8B show examples of a first transport layer or a first injection layer having a third surface.

DETAILED DESCRIPTION OF EMBODIMENTS

In order to illustrate the objects, technical solutions and advantages of the present disclosure more clearly, the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It is to be understood that the following description of the embodiments is intended to illustrate and describe the concept of the present disclosure and should not be considered to limit the present disclosure. In the specification and the drawings, the same or similar reference numerals refer to the same or similar components or members. For the sake of clarity, the drawings are not necessarily drawn to scale, and some of the well-known components and structures may be omitted in the drawings.

Unless otherwise defined, technical terms or scientific terms used in the present disclosure are intended to be understood as having the ordinary meaning for those skilled in the art. The words “first”, “second” and the like used in the present disclosure are not intended to indicate any order, number, or priority, but to distinguish different components. The word “a” or “an” does not exclude a plurality. The word “comprising” or “including” and the like mean that the element or item before the word is intended to encompass the element, the item and the like recited after the word, and not exclude other element or item. The word “connect” or “couple” and the like are not limited to physical or mechanical connections, but may include electrical connections, including direct or indirect connections. The words “upper”, “lower”, “left”, “right”, “top”, “bottom” and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, their relative positional relationship may also change accordingly. When an element, such as a layer, a film, a region or a substrate, is referred to as being “on” or “under” another element, the element can be “on” or “under” another element “directly”. Alternatively, there may be intermediate elements between them.

As illustrated in FIG. 1 and FIG. 2, embodiments of the present disclosure provide a display panel. The display panel includes: a base substrate 1, a first electrode layer 2, a light emitting layer 3 and a second electrode layer 4. The first electrode layer 2 may be arranged on a side of the base substrate 1 (in FIG. 1, it is the upper side of the base substrate 1). The light emitting layer 3 may be arranged on a side of the first electrode layer 2 facing away from the base substrate 1 (in FIG. 1, it is the upper side of the first electrode layer 2). The second electrode layer 4 may be arranged on a side of the light emitting layer 3 facing away from the first electrode layer 2 (in FIG. 1, it is the upper side of the light emitting layer 3). The second electrode layer 4 has a first surface 11 which is a roughened surface.

In the present application, the term “roughened surface” means a surface that is not smooth and has a height difference between the highest point and the lowest point on the surface greater than a predetermined threshold. For example, the roughened surface may be provided with a plurality of protrusions 111 thereon, as shown in FIG. 1. However, embodiments of the present disclosure are not limited to this. Regular or irregular patterns in a form of such as recesses or grains may be formed on the roughened surface. The above predetermined threshold may for example be greater than or equal to 50 nanometers, such as in a range between 50 nanometers and 100 micrometers, even several millimeters.

In some embodiments, the base substrate 1 is used to provide a fundamental support for the display panel and may carry other functional layers in the display panel. For example, the base substrate 1 may be a glass substrate. The first electrode layer 2 may be formed on a side of the glass substrate. In practical operation of the display panel, the first electrode layer 2 may be electrically connected to an anode of a power supply and used as an anode layer. In some embodiments, the first electrode layer 2 may be a metal electrode film. The metal electrode film not only can be used as the anode of the power supply, but also can reflect a light. In this way, the light emitted from the light emitting layer 3 can be reflected by the first electrode layer 2 back after it is irradiated on the first electrode layer 2, so as to enhance luminous efficiency of the display panel. The light emitting layer 3 may be formed on a side of the first electrode layer 2 facing away from the base substrate 1. The light emitting layer 3 may be made from luminescent materials. For example, the light emitting layer 3 may be made from quantum dot materials. The quantum dot is a semiconductor in order of nanometer. The quantum dot may emit a light with a special frequency when it is applied by a certain electrical field or light pressure, so as to be used as a light source of the display panel. The second electrode layer 4 is formed on a side of the light emitting layer 3 facing away from the first electrode layer 2. The second electrode layer 4 may be electrically connected to a cathode of power supply and thus be used as a cathode layer. For example, the second electrode layer 4 may be an indium tin oxide (ITO) layer or an indium zinc oxide (IZO) layer. The light emitted from the light emitting layer 3 may be transmitted through the second electrode layer 4 to exit. Thus, the second electrode layer 4 may include a transparent electrode. When a voltage is applied across the first electrode layer 2 and the second electrode layer 4, an electrical field will be generated between the first electrode layer 2 and the second electrode layer 4. Under the electrical field, the light emitting layer 3 can emit a light. In addition, the first surface 11 of the second electrode layer 4 may be the roughened surface. When the light is irradiated on the first surface 11, it may be reflected diffusely.

Since the first surface 11 of the second electrode layer 4 is the roughened surface, when a light beam emitted from the light emitting layer 3 enters the second electrode layer 4, an incident angle of the light beam onto the first surface 11 can be changed such that most of the light beam emitted from the light emitting layer 3 can be transmitted through the second electrode layer 4 to exit. In this way, it can enhance luminous efficiency of the display panel to ensure quality of the display device.

Embodiments of the present disclosure provide a display panel having an increased luminous efficiency. Customarily, surfaces on both sides of an electrode layer (such as ITO layer) in a conventional display panel are planar. When a light beam emitted from a light emitting layer passes through the electrode layer, a part of the light beam may be reflected totally within the electrode layer due to its incident angle greater than the critical angle of total reflection such that the part of the light beam cannot exit from the electrode layer. It may reduce the luminous efficiency of the display device and degrade quality of the display device. In contrast, the display panel provided by embodiments of the present disclosure includes: the base substrate 1, the first electrode layer 2, the light emitting layer 3 and the second electrode layer 4. The first electrode layer 2 is arranged on a side of the base substrate 1. The light emitting layer 3 is arranged on a side of the first electrode layer 2 facing away from the base substrate 1. The second electrode layer 4 is arranged on a side of the light emitting layer 3 facing away from the first electrode layer 2. The second electrode layer 4 has a first surface 11 which is a roughened surface. The first surface 11 of the second electrode layer 4 is the roughened surface, thus when the light beam emitted from the light emitting layer 3 enters the second electrode layer 4, an incident angle of the light beam onto the first surface 11 can be diversified (in various kinds) such that the light beam emitted from the light emitting layer 3 can be transmitted through the second electrode layer 4 to exit. In this way, it can increase luminous efficiency of the display panel to ensure quality of the display device.

When the second electrode layer 4 is produced, it is typically formed by sputtering. In order to facilitate forming the roughened surface of the second electrode layer 4, in some embodiments, the first surface 11 may be located on the side of the second electrode layer 4 facing away from the light emitting layer 3. In particular, at first, the light emitting layer 3 is formed, then, the second electrode layer 4 is formed on a side of the light emitting layer 3. For example, the second electrode 4 may be formed by sputtering through a mask. For the sake of simplifying the process for producing the second electrode layer 4, in some embodiments, the roughened surface may be formed on the side of the second electrode layer 4 facing away from the light emitting layer 3.

The above light emitting layer 3 can emit a light under the effect of the electrical field. In some embodiments, the light emitting layer 3 may be a quantum dot layer. The quantum dot is a semiconductor in order of nanometer. The quantum dot may emit a colored light beam when it is applied by a certain electrical field or light pressure. The color of the light beam depends on compositions, size and shape of the quantum dot. Thus, the form of the quantum dot can be changed such that the quantum dot can emit a pure light with peak value of intensity, so as to provide a better display color. It can improve quality of the display device.

When the light emitting layer 3 emits the light, electrons in the second electrode layer 4 may be transported into the light emitting layer 3. For the sake of convenience of transporting electrons, in some embodiments, a second transport layer 5 is provided between the second electrode layer 4 and the light emitting layer 3. The second transport layer 5 has a second surface 12 which is a roughened surface. In some embodiments, the second transport layer 5 may be made from transparent materials such as ZnO (Zinc Oxide) nano-particles. The second transport layer 5 is configured to transport electrons from the second electrode layer 4 into the light emitting layer 3. The electrons from the second electrode layer 4 meet holes in the light emitting layer 3 to achieve luminous effects. When the light emitting layer 3 emits the light beam, if surfaces on both sides of the second transport layer 5 are smooth, a part of the light beam will be reflected totally within the second transport layer 5, due to its incident angle, after the light beam enters the second transport layer 5. It may reduce luminous efficiency. In contrast, in the embodiments of the present disclosure, the second surface 12 of the second transport layer 5 is the roughened surface, thus, when the light beam enters the second transport layer 5, the second surface 12 will reflect the light beam diffusely such that the part of light beam cannot be reflected totally all along in the second transport layer 5. In this way, entirety of the light beam can exit from the second transport layer 5, so as to enhance luminous efficiency and ensure quality of the display device. In some embodiments, the second surface 12 may be located on a side of the second transport layer 5 facing towards the second electrode layer 4 (for example, as shown in FIG. 6) or on another side of the second transport layer facing towards the light emitting layer 3 (for example, as shown in FIG. 7). For example, a plurality of protrusions 121 may be provided on the second surface 12.

In some embodiments, the first electrode layer 2 may be an anode layer. The first electrode layer 2 can transport holes to the light emitting layer 3 and allow the holes to meet the electrons in the light emitting layer 3 to emit a light. In some embodiments, a first transport layer (for example a hole transport layer) 6 is provided on a side of the light emitting layer 3 facing towards the first electrode layer 2; a first injection layer (for example a hole injection layer) is provided on a side of the first transport layer 6 facing towards the first electrode layer 2. One or more of the first transport layer 6, the first injection layer 7 and the first electrode layer 2 has a third surface 13 which is a roughened surface. In the embodiments, the roughened surface can reflect the light beam diffusely. In this way, the light beam will not be reflected totally all along in the layer structure such that the light beam can be emitted from the layer structure completely to enhance luminous efficiency and ensure quality of the display device. In some embodiments, the third surface 13 is a surface of the at least one of the first transport layer 6, the first injection layer 7 or the first electrode layer 2 facing towards the base substrate 1, or a surface of the first transport layer 6 or the first injection layer 7 facing towards the second electrode layer 4. FIG. 8A and FIG. 8B show an example in which the third surface 13 is located on an upper side (first side) of the first transport layer 6 or the first injection layer 7 and another example in which the third surface 13 is located on a lower side (second side) of the first transport layer 6 or the first injection layer 7, respectively. In some embodiments, a plurality of protrusions 131 may be provided on the third surface 13.

In some embodiments, the first transport layer 6 and the first injection layer 7 are arranged between the light emitting layer 3 and the first electrode layer 1, instead of being arranged between the light emitting layer 3 and the second electrode layer 4. It is helpful to prevent the process for producing the second electrode layer 4 from destroying the first transport layer 6 and the first injection layer 7. It is in particular advantageous if the second electrode layer 4 is produced by high temperature evaporation.

In some embodiments of the present disclosure, the roughened second surface 12 and the roughened third surface 13 for example may be produced by any known processes (such as controlling parameters in a coating process to make uneven thickness of layers) or other known surface treatment processes in the art.

In another aspect, as shown in FIG. 5, embodiments of the present disclosure also provide a method 100 for manufacturing a display panel. As illustrated in FIG. 5, the method 100 may include:

Step 101 of arranging a first mask on a side of a base substrate;

Step 102 of arranging a second mask on a side of the first mask facing away from the base substrate and locating an orthographic projection of a pattern of the second mask onto the first mask within a first transmission portion of the first mask; and

Step 103 of by means of sputtering through the second mask, forming the second electrode layer 4 with a roughened surface of the display panel in a region of the base substrate exposed from the first transmission portion of the first mask.

In some embodiments, the first mask 41 is arranged on a side of the base substrate 1, so as to cover and shield some functional areas on the base substrate 1. The functional areas may include structures such as driving circuits, traces. The second electrode layer 4 does not need to be formed in these functional areas, thus these functional areas may be shielded by the first mask 41 to prevent materials for producing the second electrode layer 4 from being sputtered to the functional areas when the second electrode layer 4 is formed. As shown in FIG. 4, the first mask 41 may include a first transmission portion 411 and a first shielding portion 412. The first transmission portion 411 is a portion through which a sputtering beam can pass in a sputtering process, for example, is an opening area. The first transmission portion 411 cover the area on which the second electrode layer 4 may be formed, and the first shielding portion 412 is configured to shield the above functional areas to prevent the sputtering process from affecting the above functional areas.

In some embodiments, the second mask 42 is arranged on a side of the first mask 41 facing away from the base substrate. The second mask 42 is configured to form the second electrode layer 4 with a predetermined pattern through the first transmission portion 411 of the first mask 41. By means of cooperation of the first mask 41 and the second mask 42, the second electrode layer 4 may be formed in the predetermined area on the base substrate 1, to improve quality of the display panel.

In some embodiments, the second mask 42 may include a second shielding portion 421 and a plurality of second transmission portions 422 separated by the second shielding portion 421. The second transmission portion 422 is a portion through which a sputtering beam can pass in a sputtering process, for example, is an opening area. In some embodiments, the plurality of second transmission portions 422 may be arranged in an array, as shown in FIG. 3. For example, two adjacent second transmission portions 422 may have a pitch or interval between 100 micrometers and 500 micrometers. However, embodiments of the present disclosure are not limited to this. A gap between the first mask 41 and the second mask 42 may be kept. The gap may for example be in a range from 1 millimeter to 20 millimeters. In this way, when the second electrode layer 4 is formed by means of sputtering through the second mask 42, the sputtering beam will not pass through the second transmission portion 422 of the second mask 42 straightly, but diffuses to some extent (for example, due to large incident divergence angle of the sputtering beam or the diffraction effects of the second transmission portion 422 to the sputtering beam). More materials will be sputtered at a position within the area of the base substrate 1 directly facing the second transmission portion 422 (for example, the area defined by the orthographic projection of the second transmission portion 422 on the base substrate 1), thus a portion of larger thickness of the second electrode layer 4 is formed at the position. In contrast, less materials will be sputtered at a position within the area of the base substrate 1 directly facing the second shielding portion 421 (for example, the area defined by the orthographic projection of the second shielding portion 421 on the base substrate 1), thus a portion of less thickness of the second electrode layer 4 is formed at the position. In this way, the second electrode layer 4 having convex-concave roughened surface may be formed in the region on the base substrate 1 exposed from the transmission portion 411 of the first mask 41.

Embodiments of the present disclosure provide a method for manufacturing the display panel. It may improve luminous efficiency of the display panel. Customarily, surfaces on both sides of an electrode layer (such as ITO layer) in a conventional display panel are planar. When a light beam emitted from a light emitting layer passes through the electrode layer, a part of the light beam may be reflected totally within the electrode layer due to its incident angle greater than the critical angle of total reflection such that the part of the light beam cannot exit from the electrode layer. It may reduce the luminous efficiency of the display device and degrade quality of the display device. The method for manufacturing the display panel provided by embodiments of the present disclosure includes: arranging a first mask on a side of a base substrate; arranging a second mask on a side of the first mask facing away from the base substrate and making an orthographic projection of a pattern of the second mask onto the first mask fall within a first transmission portion of the first mask; and by means of sputtering through the second mask, forming the second electrode layer with a roughened surface of the display panel in a region of the base substrate exposed from the first transmission portion of the first mask. Because the first surface 11 of the second electrode layer 4 is the roughened surface, when the light beam enters the second electrode layer 4, an incident angle of the light beam onto the first surface 11 can be diversified such that the light beam emitted from the light emitting layer 3 can be transmitted through the second electrode layer 4 to exit. In this way, it can increase luminous efficiency of the display panel to ensure quality of the display device.

In some embodiments, before the Step 101, the method may further include:

Step 104 of forming a first electrode layer on the base substrate;

Step 105 of forming a light emitting layer on the first electrode layer; and

Step 106 of forming a second transmission layer on the light emitting layer.

In some embodiments, after the Step 104 and before the Step 105, the method may further include:

Step 107 of forming a first injection layer (such as a hole injection layer) and a first transport layer (such as a hole transport layer) in sequence on the first electrode layer.

The above steps 104 to 107 may be configured to form some structures of a light emitting diode, and are indicated by dashed boxes in FIG. 5.

In order to prevent materials for producing the second electrode layer from being sputtered to the functional areas on the base substrate in a sputtering process, in some embodiments, the step 101 further includes: keeping the first mask in contact with the base substrate (the base substrate 1 may include previously formed layers such as the first electrode layer 2, the first injection layer 7, the first transport layer 6, the light emitting layer 3 or the second transport layer 5). If there is a gap between the first mask 41 and the base substrate 1, part of the materials will be sputtered to the area of the base substrate 1 shielded by the shielding portion 412 of the first mask 41 in the sputtering process, so as to degrade quality of the display panel. In contrast, in the embodiments of the present disclosure, the first mask 41 is kept in contact with the base substrate 1 such that there are no gap between the first mask 41 and the base substrate 1. In this way, the materials will not be sputtered to the area of the base substrate 1 shielded by the shielding portion 412 of the first mask 41. It may improve quality of the display panel.

In some embodiments, the step 102 further includes: keeping a gap between the first mask and the second mask. If there are no gap between the base substrate 1 and the second mask, materials for producing the second electrode layer 4 will not be sputtered to the area of the base substrate 1 facing the second shielding portion 421. In this way, a complete second electrode layer 4 cannot be formed in the region of the base substrate 1 exposed from the transmission portion 411 of the first mask 41, and the second electrode layer 4 with the roughened surface will not be formed. In contrast, in the embodiments, the gap between the second mask 42 and the base substrate 1 is kept. When the materials for producing the second electrode layer 4 are sputtered to the base substrate 1 through the transmission portion 422 of the second mask 42, the materials can be sputtered to the area of the base substrate 1 facing the second shielding portion 421 such that the thickness of the materials on the area of the base substrate 1 facing the second shielding portion 421 is less than the thickness of the materials on the area of the base substrate 1 facing the second transmission portion 422, so as to form the roughened surface.

In another aspect, embodiments of the present disclosure also provide a display device including the display panel as described in any of the above embodiments. The display device may also be used to enhance luminous efficiency of the display device. The details will be omitted herein.

The above-described embodiments are merely illustrative, and not intended to limit the present disclosure. Those skilled in the art would understand that modifications and replacements of the present disclosure may be made without departing from the general inventive concept. These modifications and replacements should fall within the protect scope of the present disclosure. The protection scope of the disclosure should be defined by the appended claims of the present disclosure. 

What is claimed is:
 1. A display panel comprising: a base substrate; a first electrode layer on a side of the base substrate; a light emitting layer on a side of the first electrode layer facing away from the base substrate; and a second electrode layer on a side of the light emitting layer facing away from the first electrode layer, wherein the second electrode layer has a first surface which is a roughened surface.
 2. The display panel according to claim 1, wherein the first surface is located on a side of the second electrode layer facing away from the light emitting layer.
 3. The display panel according to claim 1, wherein a plurality of protrusions are distributed on the first surface.
 4. The display panel according to claim 1, wherein the light emitting layer is a quantum dot layer.
 5. The display panel according to claim 1, further comprising: a second transport layer between the second electrode layer and the light emitting layer, the second transport layer having a second surface which is a roughened surface.
 6. The display panel according to claim 5, wherein the second surface is located on a side of the second transport layer facing towards the second electrode layer or on another side of the second transport layer facing towards the light emitting layer.
 7. The display panel according to claim 1, further comprising: a first transport layer on a side of the light emitting layer facing towards the first electrode layer; and a first injection layer on a side of the first transport layer facing towards the first electrode layer, wherein at least one of the first transport layer and the first injection layer has a third surface which is a roughened surface.
 8. The display panel according to claim 7, wherein the third surface is a surface of the at least one of the first transport layer and the first injection layer facing towards the second electrode layer, or a surface of the at least one of the first transport layer and the first injection layer facing towards the base substrate.
 9. The display panel according to claim 7, wherein the first transport layer is a hole transport layer and the first injection layer is a hole injection layer.
 10. The display panel according to claim 1, wherein the second electrode layer is an indium tin oxide layer or an indium zinc oxide layer.
 11. A method for manufacturing a display panel, the method comprising: arranging a first mask on a side of a base substrate, the first mask comprising a first transmission portion and a first shielding portion; arranging a second mask on a side of the first mask facing away from the base substrate and locating an orthographic projection of a pattern of the second mask onto the first mask within the first transmission portion of the first mask; forming a second electrode layer with a roughened surface of the display panel in a region of the base substrate exposed from the first transmission portion of the first mask, by means of sputtering through the second mask.
 12. The method according to claim 11, wherein the arranging the first mask on the side of the base substrate comprises: keeping the first mask in contact with the base substrate.
 13. The method according to claim 11, wherein the arranging the second mask on the side of the first mask facing away from the base substrate and locating the orthographic projection of the pattern of the second mask onto the first mask within the first transmission portion of the first mask comprises: keeping a gap between the first mask and the second mask.
 14. The method according to claim 11, wherein the second mask comprises: a second shielding portion; and a plurality of second transmission portions separated from one another by the second shielding portion.
 15. The method according to claim 11, wherein before arranging the first mask on the side of the base substrate, the method further comprises: forming a first electrode layer on the base substrate; forming a light emitting layer on the first electrode layer; and forming a second transmission layer on the light emitting layer.
 16. The method according to claim 15, wherein after forming the first electrode layer on the base substrate and before forming the light emitting layer on the first electrode layer, the method further comprises: forming a first injection layer and a first transport layer in sequence on the first electrode layer. 